Self-powered feeder protection
13 ABB
14. Protection functions
Table 22. Low-set phase overcurrent protection, stage I> / 51
Setting range of pick-up current ‘I >’
0.1
1)
...32 x In in steps 0.001, infinite
± 3.0% x In for value < 1.2 In , ± 3.0% x I for value ≥ 1.2 In
Operate time delay (DMT) ‘t >’
0.04...64 s in steps of 0.01
Operation time accuracy definite mode
2)
± 2.0% of set value or ± 30 ms
IEC 60255-151:
Normal inverse, Very inverse, Extremely inverse, Long-time inverse
ANSI C37.112:
Moderate inverse, Normal Inverse, Very inverse, Extremely inverse
Special curves:
RI inverse, HR fuse, FR fuse
Time multiplier setting ‘k’
0.02...1.6, in steps of 0.01
Operation time accuracy
2)
IEC, ANSI, RI, HR and FR
characteristics
class E(5) or ± 30 ms
class E(7.5) or ± 30 ms of theoretical value for I> set value < 0.2
IDMT : 0.96 and DT : 0.98
1)
The relay’s minimum powering current is 0.07 x In when currents in three phase and 0.18 x In when current in a single phase.
2)
Operation time accuracy for protection functions when relay is in energised condition.
Table 23. High-set phase overcurrent protection, stage I>> / 50-1
Setting range of pick-up current ‘I >>’
0.2...32.0 x In in steps 0.001, infinite for CT variant
± 3.0% x In for value < 1.2 In , ± 3.0% x I for value ≥ 1.2 In
Definite time, Instantaneous
Operate time delay (DMT) ‘t >>’
0.04...64 s in steps of 0.01
Operation time accuracy
1)
± 2.0% of set value or ± 30 ms
1)
Operation time accuracy for protection functions when relay is in energised condition.